A professor of politics at a Scottish university said the senders of the toxic packages to UK politicians are nothing more than a set of sad individuals.

James Mitchell, head of government at the department of government at Strathclyde University, believes the Scottish National Liberation Army does not exist as a coherent organisation.

He said: "I guess they are really a lot of fringe individuals, sad individuals, who do these things and use the SNLA name.

"The chances of this being a coherent organisation modelled on let's say the INLA for example is something I very much doubt exists."

Cherie Blair was sent one of the packages

The lecturer was speaking in the wake of police reports that some 16 suspect packages, containing caustic soda, disguised as aromatherapy oil, had been sent to a number of high-profile people including prime minister's wife Cherie Blair and Liberal Democrat MSP Mike Rumbles.

A group claiming to be the Scottish National Liberation Army say they are behind the campaign.

Prof Mitchell said senior members of the Scottish National Party are always quick to condemn the so-call tartan terrorists as anti-nationalist.

And the academic believes there is some justification in it.

He said: "They campaign at times when the SNP are doing well in the polls or are about to launch a new campaign.

'Self-styled'

"And indeed we have seen evidence of that this week. The SNP launched a new campaign and these people have stolen the headlines.

"It is not nationalists who are doing this, it is people outside the SNP and if anyone is damaged by this it is the SNP."

The SNLA have done nothing to date which could be classed as particularly serious, said Prof Mitchell.

"If you go back to the 1970s and the Army of Provincial Government (APG) as they styled themselves at that time you will find that they damaged pipelines and the suchlike.

"But really they haven't damaged anyone other than themselves. On occasions some of these people who are rather incompetent have hurt themselves in the process of engaging in these activities," said Prof Mitchell.